Olympus Optical Company, Ltd.

Olympus Corporation

Norihiko Aoki

Hirofumi Tsuchida

Takayoshi Togino

Takanori Yamanashi

Atsujiro Ishii

Akira Tamagawa

Shinichi Mihara

Takeshi Hashimoto

Tsutomu Uzawa

Hiroshi Matsuzaki

Yuko Kobayashi

Masashi Hankawa

Juro Kikuchi

Kimiaki Yamamoto

Tsutomu Inanobe

Atsujirou Ishii

The invention relates to an image pickup optical system which can make a sensitive tradeoff between the precision of alignment of a decentration optical prism used as an image formation element for an electronic camera or the like with respect to an image pickup element and ease of fabrication. The invention provides an optical prism comprising three optical surfaces to . An entrance surface is suitable for incidence of light from a subject. The incident light is subjected to at least two internal reflections to turn back an optical path. The reflected light leaves the prism through an exit surface to form an image of the subject on an image pickup surface located outside of the prism. At least one of the entrance surface and exit surface is constructed of an optical surface having a combined transmission and internal reflection action. The optical prism is used in combination with a prism frame designed to be well fit therefor. Sides L and R formed in directions intersecting the directions of the entrance surface 14 and exit surface 12 are provided with protrusions L and R for mounting the optical prism to the prism frame

Image pickup optical system comprising a prism fixing member for preventing a deterioration in the capability of correcting decentration abberation, and apparatus therefore

A high-performance and low-cost image-forming optical system having a minimal number of constituent optical elements and made compact and thin by folding an optical path using reflecting surfaces arranged to minimize the number of reflections. The image-forming optical system has a first prism, a stop, and a second prism. The first prism has a first transmitting surface, a first reflecting surface, a second reflecting surface of positive power, and a second transmitting surface. The second prism has a first transmitting surface, a first reflecting surface, a second reflecting surface of positive power, and a second transmitting surface. The first transmitting surface and second reflecting surface of the first prism are the identical surface, and the first reflecting surface and second transmitting surface of the second prism are the identical surface. The image-forming optical system is approximately telecentric on the image side.

High-performance and compact image-forming optical system using prism elements

An object of the invention is to provide a compact yet high-performance finder optical system comprising an image inversion optical subsystem having a decentered reflecting surface, which enables a bright, distortion-free image to be observed. This object is achieved by locating a rotationally asymmetric surface in the image inversion optical subsystem forming part of the finder optical system.

Finder optical system

A high-performance and low-cost image-forming optical system made compact and thin by folding an optical path using reflecting surfaces having power. The optical system has a plurality of reflecting surfaces having power. Among the reflecting surfaces, a reflecting surface (12) of negative power is placed closest to the object side, and a reflecting surface (22) of positive power is placed closer to the image side than the reflecting surface (12). At least one reflecting surface (13) is provided between the reflecting surface (12) and the reflecting surface (22). An axial principal ray (1) incident on the reflecting surface (13) satisfies the condition of 45.degree.&lt;.vertline..theta..vertline., where .theta. is the angle formed between the axial principal ray and a line normal to the reflecting surface (13) in the decentration direction at a point where the axial principal ray (1) intersects the reflecting surface (13).

Image-forming optical system

A compact, thin and low-cost image-forming optical system having an optical low-pass filter, and an apparatus using the image-forming optical system. The image-forming optical system for forming an image of an object includes a stop (2), a first prism (10) placed closer to the object side than the stop (2), and a second prism (20) placed closer to the image side than the stop (2). The first prism (10) has object-side reflecting surfaces (12, 13) with an aspherical surface configuration that reflect a light beam in the prism and give a power to the light beam when reflecting it. The second prism (20) has image-side reflecting surfaces (22, 23) with an aspherical surface configuration that reflect a light beam in the prism and give a power to the light beam when reflecting it. A low-pass filter (4) for cutting off a high-frequency component is provided between the object-side reflecting surfaces (12, 13) and the image-side reflecting surfaces (22, 23).

Image-forming optical system and apparatus using the same

A real-image finder optical system having an objective optical system, an image-inverting optical system, and an ocular optical system, wherein a power is given to a reflecting surface of the image-inverting optical system that is closer to the observer side than an intermediate image, thereby achieving an increase in the finder magnification. The objective optical system has a plurality of lens units. When zooming from the wide-angle end to the telephoto end is performed, the spacing between the plurality of lens units is changed. The image-inverting optical system has a plurality of reflecting surfaces. Of the reflecting surfaces, at least one reflecting surface closer to the ocular optical system than the object image is formed from a curved reflecting surface that gives a power to a light beam. The image-inverting optical system has a rotationally asymmetric surface that corrects rotationally asymmetric decentration aberrations produced by the curved reflecting surface.

Real-image finder optical system and apparatus using the same

A high-performance real-image finder with a zoom objective optical system wherein a power is given to a reflecting surface of an image-inverting optical system to reduce the size in the direction of the thickness, and at the same time, a rotationally asymmetric surface is used in the image-inverting optical system to correct rotationally asymmetric decentration aberrations. The zoom objective optical system Ob has a first lens unit G1 of negative power, a second lens unit G2 of positive power, and a third lens unit G3 of positive or negative power. The real-image finder further includes an image-inverting optical system PP for erecting an intermediate image formed by the objective optical system Ob, and an ocular optical system Oc having a positive refracting power. At least one of reflecting surfaces S.sub.8 and S.sub.9 of the image-inverting optical system PP is a curved reflecting mirror having an optical power and has a rotationally asymmetric surface configuration that corrects decentration aberrations produced by the curved reflecting mirror.

Real-image zoom finder with rotationally asymmetric surface

An optical low pass filter having an optical axis common to an imaging optical system or configured as a portion of an imaging optical system for contribution to formation of an image, functioning to image components in a longitudinal direction of the image pickup device onto a desired imaging location and having refractive powers, for components in different directions, which are different from that for the components in the longitudinal direction. This optical low pass filter is suited for use with line sensors.

Optical low pass filter

The invention provides a compact, lightweight yet low-cost zoom lens system which has a zoom ratio of at least about 2 and is well corrected for various aberrations, and in which sufficient attention is paid to temperature compensation when plastic lenses are used. The zoom lens system comprises in order from an object side a front lens group GF including a plurality of positive lenses containing at least a plastic lens and having a positive refracting power as a whole, and a rear lens group GR composed only of a plurality of negative lenses containing at least a plastic lens, wherein zooming is carried out by varying the spacing between the front and rear lens groups, and all the lenses satisfy the following condition (1):

Zoom lens system

An optical system comprising a plural number of lens elements at least one of which is designed as a graded refractive index lens element having refractive index distribution in the radial direction, and has aberrations favorably corrected in said optical system as a whole by making most of the correcting functions of the graded refractive index lens element for Petzval's sum and chromatic aberration.

Optical system comprising graded refractive index lens element

The invention provides a zooming lens system which covers a wide-angle zone, has a zooming ratio of approximately 3 or higher, and is well corrected for various aberrations. This system comprises, in order from the object side, a first lens unit I having positive refracting power, a second lens unit II having negative refracting power, a third lens unit III having positive refracting power, a fourth lens unit IV having positive refracting power and a fifth lens unit V having positive refracting power, with at least said first, third, fourth and fifth lens units being moved toward the object side for zooming from the wide-angle end to the telephoto end, and conforms to the following conditions:

Zooming lens system

A wide-angle lens system comprising, in order from the object side, a front unit, a stop and a rear unit: the front unit comprising, in order from the object side, a first lens unit which comprises a plurality of lens components including a positive lens component and has a negative refractive power as a whole, a negative lens component having a concave surface on the object side and a cemented lens component; and the rear unit comprising a negative lens component disposed on the side of the stop and at least two positive lens components. This wide-angle lens system has sufficiently corrected aberrations, in particular, negative distortion, curvature of field and sagittal coma.

Wide-angle lens system #6

An optical system comprising, in the order from the object side, an objective lens unit having a positive refractive power, a relay lens unit having a positive refractive power and an eyepiece lens unit having a positive refractive power, adapted in such a manner that an inverted image formed by the objective lens unit is inverted once again by the relay lens unit for forming an erect image, using at least one graded refractive index lens element in the relay lens unit, and having a small number of lens elements or a high magnification and favorably corrected aberrations.

Viewfinder optical system

A compact vari-focal lens system comprising, in the order from the object side, a first lens unit having a positive refractive power, a second lens unit having a positive refractive power and a third lens unit having a negative refractive power, and uses at least one radial type graded refractive index lens element arranged at the image side location in the second lens unit. The vari-focal lens system has a high vari-focal ratio and aberrations corrected favorably over the entire vari-focal range from the wide position to the tele position, and consists of a very small number of lens elements.

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Tokyo, Japan

Norihiko Aoki